ISO Class 0 Oil-Free Water Lubricated Screw Air Compressor | KWI Series Stainless Steel Design | Kotech Group
The KWI Series utilizes pure water to lubricate, seal, and cool, ensuring 100% oil-free air certified to ISO Class 0. Featuring premium stainless steel rotors and advanced VSD technology, it delivers high-efficiency performance for pharmaceutical, food processing, and textile industries where air purity is critical.
Specify your industry and required air flow. Our engineers will provide a customized KWI solution and a competitive quotation within 24 hours.
- Working pressure range
- 7-12.5 bar
- Air delivery coverage
- 1.1-77 m3/min
- Broad power range
- 7.5-355 kW
- Guaranteed oil-free purity
- 100%
- TÜV certified quality
- ISO Class 0
- Oil content in compressed air
- 0 ppm
- Zero oil risk pure medium
- Water Lubricated
- Isothermal compression design
- High Efficiency
Why KWI Series Leads in Oil-Free Water Lubricated Technology
Built for the most demanding sterile environments, the KWI series replaces traditional oil with pure water as the cooling and sealing medium. This ensures 100% oil-free air while utilizing high-grade stainless steel components to provide a corrosion-free, energy-efficient solution that lowers your total cost of ownership.
100% Oil-free compression using pure water as the lubricant, cooling, and sealing medium. All-stainless steel main engine (rotors and casing) for zero corrosion and long life. Near-isothermal compression provides higher volumetric efficiency than dry screw types. Lower maintenance costs with no expensive oil filters or waste oil disposal needed. VSD (Variable Speed Drive) optional for maximum energy savings under fluctuating loads. Integrated water filtration system ensures constant cooling water purity and air end protection.
- Risk of expensive product recalls due to oil contamination in dry screw systems.
- High energy bills caused by inefficient high-temperature dry compression cycles.
- Internal rust and scale buildup in low-quality water-injected compressors.
- Frequent downtime and high cost of specialized oil-free maintenance.
The KWI Solution: Pure Air Without Compromise
- Water lubrication technology completely eliminates oil from the entire compression process.
- Superior cooling properties of water enable high-efficiency, low-temperature running.
- High-grade stainless steel construction ensures a lifetime of rust-free operation.
- Simplified maintenance design focuses on basic water and air filtration, reducing TCO.
Recommended Applications
The KWI series is the gold standard for industries where even a single drop of oil can lead to catastrophic product recalls. This model is engineered for 24/7 continuous operation in environments requiring the highest level of sterile, oil-free compressed air.
The undisputed leader of prevent global warming, Energy conservation, and environment protection
The power consumption of air compressor is occupied about 5% among a regional total power consumption. In Particular, due to the power consumption of the compressor takes up 20% ~ 30% of the total power consumption in a plant, cuts down the power consumption of the compressor is the most effective energy saving way.
High-efficiency energy-saving single screw compressor is contributing to prevent of global warming by reducing CO2. In addition, due to using no oil, not only the best way to resolve environment and energy conservation but also ISO14000 measures in water pollution and waste management and HACCP hygiene operations. Moreover, it is very safety from heat ignition due to relatively low compression temperature at about 40℃.
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100% Oil Free Water Lubricated Screw Air Compressor[/caption]
Single-Screw —- Ideal compression mechanism
A simple construction and water-seal effect deliver ideal operating efficiency.
The “Single-Screw” pump’s construction use a single screw rotor and two gate rotors, one placed on either side of the screw rotor.
This is simple construction transmits pressure to the rotating axle with good balance, and prevents excessive load on the bearings this is one of the reasons for the “Single-Screw” pump’s high efficiency. The water used as a lubricating medium also seals gaps inside the compression chamber.
Compressed air is thus kept from leaking, enabling the “Single-Screw” pump to generate sufficient discharge even at low rotating speeds. This reduces both noise and vibration. The cooling effect of the water lubricant also prevent heating from the compression process (the discharge air temperature is about 40℃.), making the compression process more efficient and eliminating the need for a cooling apparatus.
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100% Oil Free Water Lubricated Screw Air Compressor[/caption]
This improves both safety and durability significantly. The fusion of our unique compression mechanism and new water – lubricant technology is helping greatly to improve energy in a wide range of fields.
Precision processing techniques of high reliabilityThe center of the rotor has characteristics of SINGLE-SCREW consumption structure that shows high efficiency and stability by utilizing super precision technology of Mitsui Seiki that is also a maker of machine tools.
Technical Specifications of KWI Series Air Compressors for Water Well Drilling
| Model | Working Pressure-psig | Working Pressure-bar | Air Delivery-cfm | Air Delivery-m3/min | Motor Power-kw/hp | Type of Cooling | Dimension(mm)-L | Dimension(mm)-W | Dimension(mm)-H | Weight-kg | Output pipe Diameter |
|---|---|---|---|---|---|---|---|---|---|---|---|
| KWI-7.5A | 100 / 116 / 145 / 181 | 7 / 8 / 10 / 12.5 | 38.8 / 35.3 / 30.0 / 24.7 | 1.1 / 1 / 0.85 / 0.7 | 7.5/10 | Air / Water Cooling | 1300 | 800 | 1300 | 500 | 3/4" |
| KWI-11A | 100 / 116 / 145 / 181 | 7 / 8 / 10 / 12.5 | 63.6 / 58.3 / 53.0 / 45.9 | 1.8 / 1.65 / 1.5 / 1.3 | 11/15 | Air / Water Cooling | 1300 | 800 | 1300 | 540 | 1" |
| KWI-15A | 100 / 116 / 145 / 181 | 7 / 8 / 10 / 12.5 | 84.7 / 77.7 / 74.2 / 63.6 | 2.4 / 2.2 / 2.1 / 1.8 | 15/20 | Air / Water Cooling | 1620 | 1004 | 1410 | 650 | 1" |
| KWI-18.5A | 100 / 116 / 145 / 181 | 7 / 8 / 10 / 12.5 | 109.5 / 102.4 / 95.3 / 81.2 | 3.1 / 2.9 / 2.7 / 2.3 | 18.5/25 | Air / Water Cooling | 1600 | 910 | 1350 | 840 | 1" |
| KWI-22A | 100 / 116 / 145 / 181 | 7 / 8 / 10 / 12.5 | 134.2 / 127.1 / 113.0 / 88.3 | 3.8 / 3.6 / 3.2 / 2.5 | 22/30 | Air / Water Cooling | 1450 | 1000 | 1560 | 870 | 1" |
| KWI-30A | 100 / 116 / 145 / 181 | 7 / 8 / 10 / 12.5 | 187.1 / 176.6 / 151.8 / 127.1 | 5.3 / 5 / 4.3 / 3.6 | 30/40 | Air / Water Cooling | 1950 | 1050 | 1432 | 980 | 1 1/4" |
| KWI-37A | 100 / 116 / 145 / 181 | 7 / 8 / 10 / 12.5 | 233.0 / 218.9 / 201.3 / 162.4 | 6.6 / 6.2 / 5.7 / 4.6 | 37/50 | Air / Water Cooling | 1700 | 1100 | 1630 | 1000 | 11/4" |
| KWI-45A | 100 / 116 / 145 / 181 | 7 / 8 / 10 / 12.5 | 282.5 / 271.9 / 243.6 / 211.9 | 8 / 7.7 / 6.9 / 6 | 45/60 | Air / Water Cooling | 2150 | 1300 | 1590 | 1060 | 11/2" |
| KWI-55A | 100 / 116 / 145 / 181 | 7 / 8 / 10 / 12.5 | 370.8 / 346.0 / 307.2 / 257.8 | 10.5 / 9.8 / 8.7 / 7.3 | 55/75 | Air / Water Cooling | 2200 | 1400 | 1540 | 1250 | 2" |
| KWI-75A | 100 / 116 / 145 | 7 / 8 / 10 | 480.2 / 459.0 / 409.6 | 13.6 / 13 / 11.6 | 75/100 | Air / Water Cooling | 2400 | 1450 | 1740 | 1480 | 2" |
| KWI-90A | 100 / 116 / 145 | 7 / 8 / 10 | 572.0 / 547.3 / 494.3 | 16.2 / 15.5 / 14 | 90/120 | Air / Water Cooling | 2550 | 1400 | 1605 | 2030 | DN50 |
| KWI-110W | 100 / 116 / 145 | 7 / 8 / 10 | 734.4 / 688.5 / 582.6 | 20.8 / 19.5 / 16.5 | 110/150 | Air / Water Cooling | 2700 | 1550 | 1750 | 2450 | DN65 |
| KWI-132W | 100 / 116 / 145 | 7 / 8 / 10 | 847.7 / 812.1 / 706.2 | 24 / 23 / 20 | 132/175 | Air / Water Cooling | 2600 | 1650 | 1750 | 2850 | DN65 |
| KWI-160W | 100 / 116 / 145 | 7 / 8 / 10 | 981.6 / 935.7 / 829.8 | 27.8 / 26.5 / 23.5 | 160/200 | Air / Water Cooling | 3300 | 2200 | 2000 | 3750 | DN65 |
| KWI-200W | 100 / 116 / 145 | 7 / 8 / 10 | 1218.2 / 1165.2 / 988.7 | 34.5 / 33 / 28 | 200/270 | Air / Water Cooling | 3300 | 2200 | 2200 | 4100 | DN80 |
| KWI-250W | 100 / 116 / 145 | 7 / 8 / 10 | 1518.3 / 1412.4 / 1306.5 | 43 / 40 / 37 | 250/330 | Air / Water Cooling | 3670 | 2070 | 2370 | 4750 | DN125 |
| KWI-280W | 100 / 116 / 145 | 7 / 8 / 10 | 1800.8 / 1765.5 / 1589.0 | 51 / 50 / 45 | 280/375 | Air / Water Cooling | 4000 | 2000 | 2100 | / | DN150 |
| KWI-315W | 100 / 116 / 145 | 7 / 8 / 10 | 1977.4 / 1942.1 / 1730.2 | 56 / 55 / 49 | 315/420 | Air / Water Cooling | 4600 | 2300 | 2400 | / | DN125 |
| KWI-400W | 100 / 116 / 145 | 7 / 8 / 10 | 2259.8 / 2471.7 / 2153.9 | 64 / 70 / 61 | 400/550 | Air / Water Cooling | 4600 | 2300 | 2400 | / | DN150 |
| KWI-450W | 100 / 116 / 145 | 7 / 8 / 10 | 2860.1 / 2789.5 / 2471.7 | 81 / 79 / 70 | 450/600 | Air / Water Cooling | 5500 | 2590 | 2800 | / | DN175 |
| KWI-500W | 100 / 116 / 145 | 7 / 8 / 10 | 3142.6 / 3072.0 / 2718.9 | 89 / 87 / 77 | 500/670 | Air / Water Cooling | 5500 | 2590 | 2800 | / | DN200 |
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Frequently Asked Questions
Unlike traditional compressors that use oil for sealing and cooling, the KWI series uses pure water as the lubricating medium. Since there is no oil present in the entire compression system, there is zero risk of oil contamination, ensuring your air meets the strict ISO 8573-1 Class 0 standard.
Not at all. We use high-grade stainless steel for the screw rotors, casings, and piping systems. This specialized material design prevents corrosion and ensures the long-term durability of the air end while maintaining the purity of the compressed air.
Water has a much higher heat absorption capacity than oil. This allows for near-isothermal compression, which is highly efficient. Combined with our VSD (Variable Speed Drive) technology, the KWI series can reduce energy consumption by up to 35% compared to standard fixed-speed compressors.
Actually, it’s simpler and more cost-effective. You don't need to purchase expensive oil filters or deal with waste oil disposal. The primary maintenance involves changing the water filter and air filter. The system even features an automatic water exchange and filtration system to keep the lubrication water clean.
Dry oil-free compressors are often much more expensive and run at higher temperatures. The KWI series provides the same "Class 0" air quality but at a lower initial investment and lower operating temperatures, which extends the lifespan of the seals and bearings.
Yes, the KWI series is designed for heavy-duty industrial applications. The water-lubricated system provides superior cooling performance, allowing the machine to maintain a stable temperature even during continuous full-load operation in demanding environments like pharmaceutical or textile plants.
The compressor is equipped with a built-in high-precision water filtration and reverse osmosis system (optional based on model). This ensures that the lubricating water remains within the required purity levels, protecting the air end from scaling or mineral buildup.
